Hello there !
Here is a Youtube thing that was started a year ago, called "accent tag". It was asking English speakers to pronounce a list of words in order to map out all the accents in the world, in every English speaking country.
There are a few about Essex, but here is the one that sounds the most pronounced (notice the "th", the absence of "t", ...)
Here is a typical London accent, called the Cockney accent. It is in fact more than an accent because it also uses different vocabulary at times. In this video a voice coach explains what characterises the cockney accent, though he doesn't explain that "th" is pronounced "v" or "f" and the the "h" is dropped entirely.
The monologue starts at 3'18.